Design of a novel -NOON- tetradentate Schiff-base scaffold supported by α-tetralone and benzothiazole moieties with its Cu2+, Co2+, and Cd2+ chelates

Abstract

A novel organic moiety of Schiff base ligand, N-(benzothiazol-2-yl)-3-(2-(3,4-dihydronaphthalen-1(2H)-ylidene)hydrazinyl)-3-oxopropanamide (α-H2T) enriched with four active sites of coordination, was synthesized via the condensation of N-(benzothiazol-2-yl)-3-hydrazinyl-3-oxopropanamide with α-tetralone. This ligand was introduced to prepare a series of bivalent transition metal complexes using Cu2+, Co2+, and Cd2+ which were investigated by various spectral techniques (IR, UV–Visible, 1HNMR , 13CNMR , MS, and XRD) besides, elemental, magnetic and thermal (TG/DTA) analyses. The decomposition kinetics of metal complexes was evaluated by the use of Coats-Redfern (CR) and Horowitz-Metzger (HM) models. In addition, the DFT method was performed using (GGA/RPBE) functions and (DNP) basis set to inspect geometric optimized structures of the isolated solid compounds. Moreover, cyclic voltammetry studies were applied to all metal cations in the absence (and presence) of (α-H2T) ligand to clarify the ligation effect on the electrochemical attitude of metal ions through the shift in redox peaks potentials and the change in values of solvation and kinetic parameters. Finally, the biological studies including antimicrobial, antioxidant, cytotoxicity, and DNA binding were completed on the free ligand, metal complexes, and metal salts individually.